Is this a vpn service you are buying or one you've set up yourself or work set up?_________________Asus m5a99fx, FX 8320 - amd64-multilib, 3.15.9-zen, glibc-2.19, gcc-4.9.2, eudev
xorg-server-1.16, openbox w/lxpanel, nouveau, oss4(2011)

I don't run a server but use a pay one, so I'm not sure what goes into that end.

Good luck

Edit to add: Is it losing connectivity while active or idle?

Is more than one computer trying to connect to the server with the same cert?_________________Asus m5a99fx, FX 8320 - amd64-multilib, 3.15.9-zen, glibc-2.19, gcc-4.9.2, eudev
xorg-server-1.16, openbox w/lxpanel, nouveau, oss4(2011)

You can't connect to a server with different machines, using the same cert at the same time.
I have read where it causes some machines to lose connectivity.
I don't use more than one machine at a time, so I can't try it out.